Carburetor



Nov. 10, 1936. w. c. RAYFIELD CARBURETOR Filed Feb. 7, 1934 I 4 Shets-Sheet l Mill;

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' CARBURETOR Filed Feb. 7, 1934 4 ysheets-sheen s Fla 3 .ugs

INVENTOR BY Why ATT NEY Nov. 1o, 1936. W. RAYFIELD g 2,060,747

CARBURETOR Filed Feb. 7, 1934 4 Sheets-Sheet 4 INVENTOR BYl/lam @wf/M MM; ATTORNEY Patented Nov. 10, 1936 UNITED STATES PATENTQFFIC'E A.

A v camioneros. william o. Rayuela, Detroit, Mien., assignmto lDetroit Lubricator Company, corporation of Michigan Detroit, Mich., a

Application February 7, 195.4, Serial No. 710,068

17 claims. (oraal-34) cylindrical, having alaterally projecting, suri My invention relates to new and useful improvements incarburetors, and more particularly to 'a carburetor forsupplying a mixture of fuel and air to an internal combustion engine.

An object of my invention is to-provide a carburetor which will operate efficiently to supply the desired ratio of fuel to air in accordance with the needs of the engine supplied thereby.

i Another object is to provide a carburetor having provision for increasing the ratio of fuel to air at the will of the operator for starting and warming-up operations of the engine. Another object is to provide means for automatically increasing the volume of the fuel mixture supplied to the engine during the starting and warming-up periods of operation.

' Another object is to provide a carburetor having means to increase the ratio of fuel to air for engine acceleration andfor high power demands of the engine. Y

The invention consi'sts in the improved construction andcombination of parts. to be more fully described hereinafter and the novelty oi' which will be particularly pointed out and dis` tinctly claimed.

In the accompanying drawings, to be taken as a part of this specification, I have .fully and clearly illustrated a preferred embodiment of my invention, in which drawings- Figure l is a view in side elevation of the carburetor of my invention;

Fig. 2 is a top plan view thereof; Fig. 3 is a view in section on the line 3--3 of Fig. l;

Fig. 4 is a view in section on the line 4-4 of Fig. 3;

Fig. 5 is a detail view, partly in section, on the line 5 5 of Fig. 2; I

Fig. 6 is a detail view-in section on. the line 6-6 40 of Fig. 5; Fig. 7 is a detail view in section on the line 'l-'I of Fig. 2;

Fig. 8 is a detail view in section on lthe line 8-8 of Fig. 5, and

Fig. 9 is a diagrammatic View showing the ports and passageways and the interrelation of the parts of the carburetor.

. Referring to the drawings by characters of reference, I designates generally the hollow body member or casing of a carburetor, shown as of thedowndraft type, and includes an air inlet kmember 2, a mixing chamber member 3 and a throttle body member 4. These members are preferably secured together and mounted in ver- 55 tical alignment to provide an, open-ended, ,ver-

tically extending,v main mixture passageway therethrough, includingI an air inlet` 5, a mixing chamber B and a mixture outlet 1. The throttle body membernkwhich includes the outlet 'l and 50 part of chamber 6, is preferably substantially rounding flange 8 at itsjlower 'end' provided with stud or bolt,receivingaperturesll by which the 'carburetor may be secured to the engine inlet manifold or block, not shown. At itsupper end the member 4 has a lateral surrounding ilange lllon which is seated the lower end of the mixing chamber member 3 which is also provided with a lateral surrounding flange. II. 'I'he Amembers 3 and 4 are tightly clamped together by'screws "or bolts I2 extending through the flange Il) and threaded into the flange II. The passageway throughthe mixing chamber member 3 is preferably substantially rectangular in plan for cooperation with pivotedsuction operated means, to be described. At its upper end, the member 3 is provided with a lateral surrounding ange I3 which receives a lateral surrounding ilange I 4 onthe lower en'dof the air inlet member 2. The flanges I3 and I4 are rigldlyclamped together by bolts, or the like, I5 to secure the members 2 and 3 tightly together. The joints between the flanges I0 and il and between the flanges I3 and I4 are preferably provided with gaskets to insure a tight joint and prevent leakage. The air inlet member 2 is preferably provided with downward and inward tapering, internal, side walls c on- `verging in the direction of air flow to increase the velocity of air flowing through the air inlet 5. Positioned centrally within the inlet 5 a-nd extending longitudinally thereof, there is a dashpot casing or housing I 'l which ls-hollow and .A

ihecasing il, the member 2, and the vsupportingA members I 8 are preferably integrally formed as by die casting, or the like.- The upper open end of the casing Il is internally lscrew-tlireadedl to receive a hollow closure member or plug I9 having a lateral, circumferential flange adapted to clamp a gasket against the tcp end face koicasing Il.'

Supported in the plug member I9 and projecting freely through an aperture in the inner endwall thereof into casing STI thereis a fuel meteringpinf 2li. The pin 2@ is preferably in the form of a tapered needle valve and is 'universally'.suppor'ted,

as at 2i, in an adjustable stem member 22. The.

member 22 has screw-threaded engagement, as

at 23, with ,the internal wall of the plug member l I' so that rotation or theA member 224williad`just the valve or pin 20 longitudinally. The member [I9 isprovided above its internally'th'readed' por,-

tion with a packing recess 24v surrounding the member 22. Within the recess 24 there is packing m-aterial 25 held under compression by con spring 26 to prevent leakage around the stem 22. The spring 26 is held under compression and within the recess 24 by an annular end plate or washer 21 which surrounds stem 22 and which closes the top open end of the recess 24. The washer 21v is preferably rigidly fixed in position by forcing the metal of the member I8 over thereon, as at 28. Within the casing |1 there is a dash-pot chamber 23 in which there is a dash-` pot piston 30 having a hollow open-ended stem 3| which projects out of the lower open end of the casing I1. The stem 3| is rigid with piston 3|! and serves as a nozzle tube having its bore or passageway 32 opening, as at 32, through the piston 30 to provide a fuel supply port. Themetering valve 2li extends into the inlet port 32a and cooperates therewith to meter fuel flow through the passageway 32. The lower end portion of the casing I1 is of reduced internal diameter, as at 33, to provide a guideway in which the nozzle tube 3| has a free sliding fit, thereby closing the lower en d of the chamber 29 and also providing an upward facing, annular shoulder 34 surrounding the tube 3|. Positioned within the chamber 29 and held under compression between the shoulder 34 and the piston 30, there is ahelical coil spring 35 which surrounds the tube 3| and which normally tends to move the piston 30 relative to the valve 20 to reduce the effective flow area of the annular inlet port 32a. Through the stem 3| substantially in the plane of its juncture with the piston 30, there is a small vent or bleed port 35 preferably of about 0.028 inch diameter and which serves to relieve the dash-pot chamber of fuel vapor or gas bubbles. When the engine is hot, the liquid fuel in the dash-pot chamber 29 will boil and unless some venting means such as port 35*l is provided, the gas bubbles will collect in the bore of casing |1 above the piston. These bubbles if permitted to so collect will obstruct the annular orifice around pin 20 and intermittently resist the free passage of liquid fuel through port 32* causing uneven feeding offuel to bore l32 and surging of the engine. The port 35EL permits the bubbles to -by-pass the port 32a and pass directly from the dash-pot chamber into the bore 32. Secured on the projecting end of the stem or tube 3| there lis a nozzlemember 36 having a sleeve portion 31 which surrounds and receives the reduced lower end portion of the casing |1. Within the outlet end of the passageway 32, there is a calibrated plug 38 having a marginal flangewhich overlies the end of the tube 3| so than the plug as is heid in position by the nozzle member 36. The plug member 38 defines the main nozzle jet and determines the maximum flow area ofthe passageway 32. The nozzle member 36 is preferably provided with a plurality of intersecting radial slots 39 which serve to diffuse and break up the fuel/discharged from the nozzle. Supported on the flange I3 or upper end wall of member 3 and extending across the main passageway through casing I, there are substantially parallel bearing shafts 40 which are positioned adjacent one pair of the opposite side walls of member 3 and have their opposite ends confined within downward open recesses 4|v formed in the underface of the flange |4, see Fig. 3. Journaled on the shafts 48 for downward swinging movement, there are air valve or vane members 42 which converge downward into engaging relation with each other, as at 42", within the member 3 to substantially close the main passageway through the casing 'Ihe members 42 are preferably substantially rectangular so that they cooperate with the rectangular mixing chamber 6 to effectively control flow through the main passageway. 'I'he side edges of the members 42 transverse to shafts 40 are only sufficiently spaced from their adjacent walls so that they may have free swinging movement. Projecting from the members 42 there are operating arms or fingers 43 which extend toward the casing l1 and which terminate within a circumferential groove 44- formed in the nozzle member sleeve portion 31. The ngers 43 operatively connect the suction operated valve members 42 and the dash-pot piston 30 so that the dash-pot serves to control the opening movement of the valve members 42. It will also be noted that the valve members 42 act through the fingers 43 to regulate the annular fuel orifice around the metering pin 20 by movement of the piston 30 relative thereto. Cooperable with the vane members 42 there are a pair of deflector members 45 which converge toward each other and project from the opposite side walls of the member 3 between and within the angle formed by the vane members 42 so as to form a continuation of the converging side walls of the air inlet member 2 to direct the incoming air toward the nozzle outlet. The underside edges 46,' see Fig. 2, of the members 45 converge downward at an angle equal to the angle between the members 42 which when closed substantially seat thereon at their side edges to further effectively close the main passageway from the inlet 5. Through the engaging edges of the vane members 42, there is a substantially cylindrical aperture 41 which receives the nozzle member 36, the aperture being of slightly larger diameter than the diameter of the member 36 to provide for primary air flow when the vane members 42 are in closed position. yFlow through the main passageway and discharge from the outlet 1 is controlled by a suitable control means 48 such as a throttle valve of the butterfly type secured to the shaft 49 journaled in the side walls of the member 4 and having one end projecting therethrough to receive an operating lever 50. Rigid with the lever 50 there is an adjustable stop member 5| cooperable with a fixed abutment or stop 52 carried externally by the member 4 to limit closing movement of the throttle valve 48. The lever50 is preferably provided with a fixed stop portion 53, also cooperable with the stop member 52 to limit opening movement of the throttle valve 8 so that the throttle valve will not be rotated beyond full open position.

The mixing chamber member 3 serves to support a fuel reservoir or constant level chamber 54 which is preferably formed integrally therewith as by die casting. The chamber 54 is positioned at one side of the throttle body member 4 and preferably has a wall portion 55 in common with the chamber 6. The chamber 54 is provided with a fuel inlet passage 56 which leads into a cup 51 having an overflow edge 58 for admission of fuel to the main reservoir 59. lWithin the cup 51 there is a valve casing 60 containing a valve port 6| intermediate the ends of a passageway 62 through the casing 6U. The passageway 62 communicates at its opposite ends with the inlet 56 and the interior of the cup 51. A valve member 63 cooperates with the port 6| to control the admission of fuel to the cup 51 and the main reserreservoir 59 there is a constant level float 65 which is secured to the lever 64 and which actuates the valve 63 to maintain a constant level of liquid fuel inthe reservoir 59. The overflow edge 58 of the cup 51 is preferably above the normal constant liquid level in the reservoir 59 so that any air or gas entrained with the fuel and entering the cup 51 will be separated from the fuely at edge 58 and be released into the space in the chamber 54 above the surface of the fuel and not be carried therewith to the main nozzle. An

air inlet 66, see Figs. 2 and 3, is formed in the top edge of the side wall of the chamber 54 to admitl air at atmospheric pressure to the surface of the liquid fuel in the `reservoir 59. 'Ihe open top of the chamber 54 is closed by a cover member or plate 61 which is secured in position by screws, or the like, 68.- Liquid fuel is supplied to the dash-pot chamber 29 and to the nozzle 36 from the reservoir 59 through a conduit 69 having its inlet portion formed by a tube 10 which extends downward into the reservoir 59 between the float 65 and the wall 55. The tube 18 extends through an aperture 'il in the cover member 61 and is screw-threaded, as at 12, or otherwise secured at its upper end in an external, longitudinally extending, tubular portion or boss 13, preferably formed integral with the die cast inlet member 2. The conduit 69 extends vertically upward into the boss 13 to a point in line with one of the supporting members I8. At this point, the conduit 69 is inclined upwardly and extends, as at 14', through the boss 13, the side wall of member 2, and longitudinally through one of the supporting members I8 into the bore of casing l1 between the plug member I9 and the piston 30. Y

Supported externally by the side wall of the chamber 54 and preferably formed integral therewith, there is a vertically extending, elongated housing or casing 15. The housing 15 is hollow, y

having a substantially cylindrical bore closed at its bottom end and open at its upper end, the lower portion of the bore defining a pump chamber 16 and the upper portion of the bore comprising a valve chamber 11. The bottom end portion of the pump chamber 16 is of reduced internal diameter, as at 18, to receive an annular valve seat member 19 with which a disc check valve 88 cooperates. The seat member 19 is held in position'by a spider 8l which also serves to limit upward movement of the-valve disc away from its seat. The reduced chamber portion 18 communicates through a, port 82 with a sump 83 in the bottom of the main reservoir 59. The sump 83 is formed in a boss 84 projecting from the bottom wall of the chamber 5,4 and is provided with a drain plug 85. Within the chamber 16 there is a pump plunger or piston 86 which is normally urged upward into engagement with its operating member or piston rod 81 by a helical coil spring 88 positioned in the chamber 16 and held under compression between the bottom wall of the chamber 16 and the piston 86. ing member 81 has a free sliding fit within the vertical bore of a valve member 89 rotatably sup-- ported in the valve chamber 11. The valve member 99 projects upward out of the housing 15 and through an aperture 98 in the cover member 61.

The aperture 90v is preferably in the form of a slot opening through the side edge of the member 61, as at 9|, adjacent the mixing chamber member 3. The valve member 89 is provided with a circumferential groove 92 to receive the marginal edge of the member 61 surrounding the aperture 98 so that the valve member 89 is sup- The operatported by the cover member 61 and held thereby against vertical movement although freely rotatable in the aperture 90 -and the chamber 11. Within the bore 93 of the ,valve member 89 the operating member 81 is provided with, oppositely positioned; longitudinally extending ,recesses 94, 95. The recesses 94, 95 are in communication with each other through transverse ports 96 in the member 81 and together provide a fluid chamber. The longitudinally extending recesses 94, 95 are preferably formed by removing opposite segmental portions of the surface of the member 81 such that the oppositely directed adjacent bases of the recesses 94, 95 which are joined by the vertically spaced ports 96 are substantially parallel to each other. The fluid chamber is in communication with the pump chamber 16 by a conduit 91 comprising a central port 98 through the `piston 86 and a vertical bore extending upward into the member 81 from its lower end, the bore terminating at its upper end in a transverse port 99 opening into the recess 94. The pump chamber 16 is also in communication with the main reservoir 59 by means'of ports 99a and 99h through the wall separating the chamber and reservoir;

Fig. 3, the ports preferably inclining upward from the pump chamber into the reservoir. The normal liquid level designated by the line L-L is above' the plane of piston 86 when in its uppermost position, so that the lower end portion of conduit or passageway 91 including port 98 will at all times contain liquid fuel. When the engine is hot, the liquid fuel inchamber 16 will vaporize forming gas bubbles which if port 99? were not provided would discharge upward through conduit 91 forcing the fuel therein upward into the'uid chamber. This action which is percolation would be continuous as long as the engine was hot enough toyvaporize the fuelin the pump chamber. In addition tothe bubbles formed'within chamber 16, some bubbles may also be entrained in the entering fuel. The liquid fuel discharged into the fluid chamberby this percolation when the engine is at rest would drain into the main mixture passageway through the pump discharge jet to be described and would pocket or trap in the' inlet manifold positioned as is usual in downdraft carburetion beneath the carburetor. This trapped fuel would then prevent engine starting as the mixture supplied to the hot engine would be too rich to fire. This dilculty has been overcome by the provision of the vent port 99eY which opens intothe chamber 16 at a point substantially in line with the plane of the bottom face of the piston 86 when the piston is in its uppermost position so that any gas f bubbles entrained with fuel entering chamber 16 or formed by vaporization of the liquid fuel in chamber 16 will escape intothe reservoir 59 and not force fuel through conduit 91 into the fluid chamber and thence into the manifold. Although the conduit 91 is normally open, it has been found'that the bubbles will leave the chamber 18 via the port 99a instead of through the conduit 91, evidently due to less resistance to escape of the bubbles via port 99a. The piston has an upward projecting circumferential flange 99C which serves to close the port 99n when the piston is depressed, but even so some fuel will pass upward around the sides of the piston when it is operated. This fuel, if trapped above the piston, would prevent proper operation of the pump. so that the port 99b is provided to permit discharge into the reservoir 59 on the suction stroke of the pump of any fiel which collects thereabove. The fluid chamber is adapted to discharge fuel from the chamber 16 into the mixing chamber 6 through the bore of a registers with the outer end of the passage to establish communication between the chamber 16 and the mixing chamber 6 but which is movable out of registry with passage I0| upon rotation of the valve member 89. The valve member 89 is also provided with a port |03 normally out of registry with the passage IOI but which is so positioned relative thereto, see Figs. 6 and 8, that it comes into registry with the passage |0| as theA port |02 passes out of registry therewith upon rotation of the valve member B9. The housing 15 also includes a combined air inlet and fuel overiiow cup or chamber |04 positioned at the side of the valve chamber 11 and having a wall common to the wall of reservoir 54. The cup or chamber |04 is open to atmosphere by means of a passageway leading into the reservoir chamber 59 above the liquid level therein and formed in the top face of the common side wall of the chambers 54 and |04. The passageway |05, which is preferably in the form of an open channel, has its top closed by the cover member 61. The common wall between the valve chamber 11 and the cup |04 is provided with upper and lower ports |06, |01 respectively which establish communication between the chamber and the top and bottom of the cup |04. The fluid chamber recess 95 is normally open to atmosphere from the reservoir 59 via cup |04 through a port |08 in the valve member 89 which registers with the port |06 when the fuel port |02 is in registry with the passage IOI. The ports |06 and |08 are of sunlcient size so that when they are in full registry the rate of admission of air to the fluid chamber will be sufficient to satisfy the mixing chamber suction on the nozzle |00, thereby preventing the suction from drawing fuel through the nozzle |00 from the chamber 16. In the horizontal plane of port |08, the valve member 89 has a plurality of additional ports |08, |08b and I08 which are of successively decreasing diameters and registerable with port.|06. The fuel ports or jets |02, |03 are so positioned relative to each other and to passage |0| and to ports |08, |08 and |08", and the ports |08, |08a and |08b are so positioned relative to air inlet port |06 that as the valve member 89 is rotated clockwise of Fig. 8 to close port |02 and open port |03, the air port |08a will register with port |06. Port |08's cuts down the air admitted to-the fiuid chamber sufficiently so that the mixing chamber suction will be effective on conduit 91 and the nozzle |00 will discharge a fuel mixture into the mixing chamber. Continued clockwise rotation of member 89 will register portv |08b with port |06 thereby further decreasing the air supply to the uid chamber and since port |03 is still in registry with passage IOI, a richer fuel mixture will be fed to the mixing chamber 6 through nozzle |00. The lower port |01 is in registry with a port |09 adapted to establish communication between the cup |04 and the fluid chamber via recess 95 but the port |05 is normally closed by the operating member 91 which serves as a valve controlling the port |09. The operating member 81 also serves as a valve controlling the air inlet port |06, the length of the recess 95 being such that when the member 81 is moved downward to actuate the piston 86 y operating and suiiciently to cut off or close the port |08 and therefore the port |06, the lower end of the recess 95 will be in communication with the port |09. The valve member 89 is also provided with another port IIO which is vertically and circumferentially offset from and preferably positioned in a plane above the ports |02, |03. The port IIO is adapted to register with a priming passage or duct I I I opening at one end into the valve chamber bore 11 and at its other end I|2 discharging into the main passageway through the casing I and preferably into the outlet 1 on the posterior side of the throttle valve 48. The duct III extends substantially horizontally through a boss I I3 projecting externally from the side wall of the member 3. At a point in the boss I I3 the duct I turns downward and opens through the flange II into registry with a vertical continuation of the duct I I formed in avertical boss I I4 projecting from the external wall of the throttle body member 4. The position of the port ||0 is such that it will not come into communication with the duct I I I until the fuel port |03 is moved out of communication with the passage |0| and the port |08c is moved into communication with the air inlet |06.

'I'he valve member 89 is provided with an operating member I I5 preferably in the form of a flat plate having an aperture therethrough to receive the valve member and which rides upon the top face of the cover member 61, being held in engagement therewith by a marginal overlying flange I I6 on the valve member 89. The operating member II5 and the valve member 89 are preferably xed against relative rotation by a lug or ear |I1 projecting upward from the operating member into a slot ||8 in the flange II6. The member I|5 is provided with radially projecting stop portions I I9, |20 which cooperate with a stop member I2I projecting from the top face of the cover member 61 and positioned between the stop portions I|9, |20 to limit rotation of the valve member 89. The operating member II5 also serves to actuate a loading means |22 for the suction operated valve means 42. The loading means |22 comprises a substantially U-shaped lever member having its arms extending upward from their connecting portion which is journaled in a bearing sleeve |23 extending through and secured in the side wall of the mixing chamber member 3 such that one of the arms |24 is positioned within the chamber 6 and is movable into engagement with one of the valve members 42 and the other arm |25 is positioned externally vof the member 3. The arm |25 is connected by a pull wire or link |26 to a lug or ear |21 rigid with the operating member I|5 and projecting upward therefrom adjacent the stop member I|9. The link |26 preferably includes a coil spring |28 which transmits movement from member |I5 to arm |24 so that the valve means 42 can move toward open position against the resilient force exerted by the loading means without changing the setting of the operating member ||5. The relation of the loading means to the port |03 is preferably such that when the valve member 89 is rotated to bring the port |03 into registry with the passage IOI the arm |24 will be moved sufficiently to engage valve means 42 when closed without placing any appreciable tension on the spring |28. In this position of the operating member II5 and loading means |22, the resistance afforded by the dashpot and spring 35 to opening movement of the valvemeans 42 will be increased by the resilient der tension to resiliently urge the arm |24 against the valve means 42 when in closed position so as to materially increase the loadon the valve members 42 exerted vby the dash-pot and the spring 35. The operating member ||5 and the parts actuated thereby are preferably held in their various positions of adjustment'by a springpressed dog or detent |29 carried by the casing 15 at the sidof the -cup |04. 'I'he detent |29 is guided for reciprocation in a vertical bore |30 and extends upward through an aperturein the l cover member 61 into engagement with the unvalve member 89 will be positively positioned for registry of the valve ports with their respective passages. 'I'he operating member y| |5 is also provided with a laterally extending cam portion |32 which projects outward beyond the casing 15 and is provided on its underside with an inclined cam face |33, for a 'purpose ,to be described. The throttle operating lever 50 is connected to the operating member 8`1-which extends above the valve member 89' by Va substantially S-shaped thrust member or link |34 having one end extending into a slot |35 in the lever 50.and secured therein by. a pivot pin |36. The other end of the member |34 extends into a vertical slot |31 in the top end of the operating member 81 and is pivotally secured therein and thereto by a'pivot pin |38. .Projecting from the thrust member |34 toward the casing 15, there is an arm or bracket |39v which terminates at its free end beneath the cam portion |32. The free end portion of the arm |39l is of substantially inverted U-shaped form, see Fig. 3. Through the horizontal portion |40 .of the larm |39, there is .adjustably screwthreaded a cam follower screw |4| which projects upward into cooperable relation with the inclined camV face |33. l'A locking screw |42 vthreaded through the arms of the U-shaped bracket portion serves to clamp the cam follower |`4| rigidly in adjusted position. The length of the cam face |33 is such that' the yfollower meml ber |4| will engage the horizontal under face |43 of projecting portion |32 when the port |03 is brought into registry with the passage lol, mere-y by limiting further opening movement of the throttle valve 48 upon continued rotation of the operating member H5. Beyond the horizontal face |43 the`underside of the projecting portion '|32 is relieved, as at |44, to provide a cam face vertically offset from Aand above the plane of the face |43.l When the operating member ||5 is rotated sufficiently to bring the port intol to the manifold of an internal combustion engine and the fuel inlet 66 to have been connected to a suitable source of fuel supply, is asy follows: Prior to starting or cranking the engine, if the engine is cold the operating member will be rotated clockwise of Fig. 2 from the position shown until theA stop ||9 engages the stop member |2|. This operation will move the primer port ||0 int-o full registry with the primer duct or passage will carry the fuel ports |02 and |03 beyond the passage |0|, and will also bring the small air inlet Port |08c into registry with the air inlet port |06.

In addition to Aestablishing direct communication between the primer duct outlet ||2 andthe main reservoir 59 via the pump chamber 16, the rotation of the valve member 89 will actuate the loading` means |22 to provide a maximum load on the air inlet ,valve members 42. The rotation of the operating member 4||5 will also move-the thrust member |34 downward by engagement of the cam face |33 with its follower |4|, thereby moving the throttle valve 40 toward open position sufficiently so that stalling of the engine will be prevented. It will be noted that the complete movement of the operating member ||5 to bringthe port ||0into registry with the duct will move the throttle valve first to a prede-- termined open position by operation of cam face |33, then as the follower member |4| leaves the cam face |43 and moves upward into engagement with the face |44, the throttle valve will move `from this predetermined open position toward closed-position but not sufliciently to engage stops 5| and 52. With the iginition turned on, if the engine is now. cranked liquid fuel will be drawn through the duct together with a very small quantity of air admitted by bleed port |08c to mix with such air as can pass the additionally loaded valve members 42 through the annularlaperture 41 and the ,slightly cracked throttle valve to provide a mixture which is exceedingly rich in fuel and desirable for cold engine starting. The bleed port |08d serves primarily to decrease the weight of the liquid fuel column to aid in lifting the fuel .from chamber 16 to outlet 1 without materially affecting the fuel mixture ratio. As soon as the engine fires and is operating under its own power, the operator will move the operating member ||5 counterclockwise/ of Fig. 2 to cut down the richness of the fuel mixture, except in unusually extreme cold weather operation. In normal cold engine operation, 4the member ||5 is returned to a position whichwill cut off the port ||0 from the duct and bring the Warming-up jet or port |03 into registry with the passage |0|. The air inlet port |08b will now be in registry with air inlet port |06 so that a supplemental fuel mixture will be supplied `to chamber 6 through nozzle |00. This return movement of the operating member 5 will move the cam face |43 into engagement with the follower |4|, thereby depressing the thrust member |34 and moving the throttle valve to a further open position such as is required to maintainidling operation of the engine during the warming-upvperiod The port |03 is preferably of'smaller diameter than the port 0 andthe Iair port |08b is larger than the port |08c so that the richness of the-supplemental fuel supplied to' the mixing chamber by nozzle .|00 will be decreased. 'This' return movement of the operating member ||5 will also partly relieve the increased tension of the loading .means |22 against the valve members 42 while, however, maintaining a greater resistance to opening movement of the valve members 42 than is normally,-

exerted by the dash-pot `and the spring 35.l VIf clockwise direction thereby bringing air port |06l into registry with port |06 while maintaining the fuel port |03 in registry with nozzle passage |6| and cam face |43 in engagement with the follower |4|-. 'This will only change the mixture ratio of the supplemental fuel supply discharged by nozzle |00, that is, the ratio of air to fuel in the supplemental mixture will be increased. As the operating member ||5 is moved to normal operating position, the fuel port |02 will move into full registry with -the passage |0| and the air inlet port |06 will be moved into registry with the air inlet port |06 so that the fluid chamber comprising recesses 64 and 95 will be under substantially atmospheric pressure. As the air inlet ports |06 and |06 are of sufficient size to maintain air at substantially atmospheric pressure in the fluid chamber, fuel will not be drawn from the pump chamber 16 as the suction on the nozzle |60 will be satisfied by the air supplied to the fluid chamber. 'I'he movement of the operating member 5 to normal position, Fig. 2, will also act through the link |26 to move the loading means |22 to inactive position, as shown in Fig. 4, with the result that the valve members 42 are resisted on opening movement solely by the dash-pot piston'30 and the spring 35. This movement of the operating member ||5 to normal position when stop engages stop member |2| will also permit cam follower member |4| to move up along the cam face |33 until the cam face |33 no longer bears against the follower member |4|, thereby permitting the throttlefvalve 46 to return to substantially closed, normal idling position withstop member 6| engaging stop 62. If the throttle is gradually moved toward open position, the suction transmitted to the mixing chamber 6 will increase and cause the valve members 42 to move away from each other about theirv supporting shaft 40 and toward open position. As the valve members 42 open, they will act through the operating members 43 and the nozzle sleeve 31 to move the dash-pot piston 30 and its port 32l relative to the metering valve 26 to increase the annular fuel orifice at the entrance to the stem bore 32. This interconnection between the fuel metering means and the air metering means results in an increase of the fuel supplied by the main nozzle to the mixing chamber as the air admitted to the mixing chamber from the air inlet 5 is increased so as to maintain a desirable ratio of fuel to air during certain periods of engine operation. As the throttle moves toward open position, it will act through the thrust member |34 upon the operating member 31 and move the same downward in the bore 63. n As the member 61 moves downward. the top end edge of the recess 65 will move across the air Ainiet'port |66, land when the member 61 has decreased the air admitted to the fluid chamber from port |06 below the suction demand on the nozzle |06. then fuel will be drawn from the pump chamber 16 upward through the conduit 61 into the fluid chamber recess 64 to mix therein with the small quantity of air s'till `admitted at; port |66 and will discharge as a mixture through the port |62 andthe nozzle |00 into themixingchamby the operating member ,61.

ber to increase the ratio of fuel to air supplied to the engine as the power demand increases. Further downward movement of the operating member 61 will cut oif the air inlet port |06 but simultaneously therewith the bottom lower edge of the recess 95 will uncover the port |09 so that air admittedvto the cup |04 passage |05 from the main fuel reservoir 59 will enter the fluid chamber, but the air admitted through the port |09 which is of smaller diameter than the port |06 will be insuilcient to satisfy the mixing c'namber suction on the nozzle |00 so that a supplemental supply of fuel from pump chamber 16 and air from port |06 will continue to discharge into the mixing chamber through the nozzle |00 as the opening movement of thei throttle continues. If the throttle valve is opened quickly from substantially closed or normal running position but not far enough to uncover the port |09, there will be a momentary increase in the supply of fuel supplied to the mixing chamber to supplement the discharge from the main nozzle. This momentary supplemental discharge will be forced from the pump chamber 16 upward through the port 66 and conduit 61 into the fluid chamber recess 94 and will be forced through the nozzle |00 by the atmospheric air over the surface thereof which enters the fluid chamber through the air inlet ports |06 and |06 As soon as the fuel displaced from the pump chamber has been forced out through the nozzle |00, further discharge of fuel from the nozzle |00 will cease as the suction in the mixing chamber will again be satisfied by the air entering the fluid chamber through port |06. If the throttle valve 48 is moved quickly to full open position or sufficiently open so that port |09 is uncovered, then there will be a discharge of solid liquid fuel. from the pump chamber 16 through the conduit 91, port |02 and thev nozzle |00 into the mixing chamber as above described for part throttle acceleration. In this latter case, however, fuel entering the fluid chamber will overflow through ports |06 and |06 into the cupy |04 prior to the cut-off of the port |06 This fuel in cup |04 will be under atmospheric pressure from the rervoir 56 via passage |05 so that when the member 61 is depressed sufllciently to bring recess 65 into registry with port |09. the liquid fuel in cup |,04 will be discharged through aligned ports |01 and |06 into the fluid chamber recess 95, and thence through the lower port 66 into recess 64 for discharge through the nozzle |00 into the mixing chamber. It may be notfd that the fuel in cup |04 will not be discharged therefrom during the discharge stroke of the piston 66 but will follow after the forced discharge from the pump. When the pump stroke has been completed, the liquid fuel in cup |06 will be discharged by the atmospheric a.r over the surface thereof into the fluid chamber through port |06 which will supplement the supplemental supply of fuel drawn by mixing chamber suction on nozzle |00 through conduit 61 from the pump chamber. When cup |64 is emptied ofv fuel, the port |09 will be open to atmosphere but its size is insufilcient to satisfy the suction on the nozzle |00 vso that the forced discharge' of /fuel through nozzle |00 by the pump will be followed by fuel sucked from the chamber 16 together with some air from port |06.v This additional supply of fuel from chamber 16 and` air from inlet port |06 which follows the pump discharge acts to supplement the main mixture supply of fuel from the main nozzle 36 and air from inlet 5 create the necesi sary rich mixture for high power demands of the engine. -It will be lnoted that the supplemental supply of fuel following the pump discharge stroke decreases gradually in the ratio of fuel to air, the supplemental supply being first solid liquid fuel from lchamber 16v and cup |04, then fuel from chamber 18 mixed with air and fuel from cup |04, and finally fuel from chamber 16 and -air alone from cup |04 as the fuel supply is exas the operating member 81 is moved upward but also acts through the thrust member |34 to urge the throttle valve toward closed positiorr. The pump is operable to discharge fuel into the main mixture passage irrespective of the position of the operating member H5. If the primer port |0 is in registry with passage opening ofthe throttle 'valve will act on piston 86 to force solid liquid fuel through the jet ||2 into the outlet 1. When the warming-up port |03 is in communication with the passage |0|, the operation of the pump will be as above described in connection with discharge through the port |02, ex-

-cept that the lower discharge port |01 from cup .|04 will be closed so that any liquid fuel trapped in cup |04 will not pass to nozzle |00 upon completion of the'pump stroke, the port |08 being out ofregistry with port 01. This omission of the fuel feed from cup |04 is compensated by the richer follow up mixture fed to nozzle |00 due to the fact that air ports |08*i and |ll8b admit less air to the fluid chamber than does the port |08.

What I claim and desire to secure by Letters Patent of the United States is:

l. A carburetor comprising a hollow casing having a substantially straight vertical openended passageway therethrough, one end portion of said passageway defining an air inlet converging in the direction of flow, the other end portion of said passageway defining a mixture outlet, a dash-pot casing concentrically positioned in said air inlet in circumferentially spaced relation to` the converging walls of said passageway, supporting members bridging said air inlet and extending between said casings and rigidly supporting said dash-pot casing, the inner end of said dashpot casing being open and having a hollow extension providing guide means, a piston in said dash-pot casing having a hollow stem opening through said piston and reciprocably supported in said extension, a hollow plug member closing the outer open end of said dash-pot casing, a fuel metering valve adjustably supported in the bore of said plug member and extending into the bore of said stem to regulate flow therethrough, a yfuel reservoir, a fuel supply conduit extending from said reservoir and opening longitudinally through one of said supporting members into said dashpot casing between said piston-andl said plug member, suction operated valve means controlling air flow through said passageway, said stem having' a nozzle member discharging into said4 and means to control discharge from the outlet end of said passageway.

2. A downdraft carburetor, comprising a throttle body member, a mixing chamber member mounted on and secured to said throttle body member,an air inlet member mounted on and secured to said chamber member, said members being hollow and combining to provide-an openended passageway, a throttle valve journaled in r said throttle body member, downward converging air valve members pivotally supported in said passagewayadjacent the side walls thereof and meeting each other to close said passageway, a housing member rigidly supported in said air inlet member and containing a dash-pot chamber, a piston in said dash-pot chamber, said valve members having an'aperture therethrough, a nozzle tube connected to said piston and projecting from said housing member into said aperture, means operatively connecting said valve members and said tube for movement in unison, a metering valve extending into'the bore of said tube to meter flow therethrough, a fuel reservoir rigidly carried by said mixing chamber member andA positioned at one side of. said throttle body member, and a fuel supply conduit leading upward from said reservoir to said housing member to feed fuel to said nozzle tube.

3. A carburetor comprising a hollow casing having a passageway therethrough, main air'and fuel inlets discharging into said` passageway, a fuel reservoir supplying said fuel inlet, a supplemental fuel supply conduit-leading from said reservoir to said passageway, a valve controlling flow through said conduit, a plate member carried by said valve and movable therewith, a cam member on said plate member, a throttle valve controlling ow through said passageway and having a shaft journaled in said casing, an operating arm fixed on said shaft, a thrust member guided for reciprocation and operatively connected to said arm, and a cam follower member carried by said thrust member and cooperable with said cam member whereby movement of` said supplemental supply valve will actuate said throttle valve..

4.` A carburetor comprising a hollow casing having a passageway therethrough, main air and fuel inlets .discharging into said passageway, a fuel reservoir supplying said fuel inlet, a supplemental fuel supply conduit leading from said reservoir tosa'id passageway, a valve controlling flow through said conduit, a plate member carried by said valve and movable therewith, acam mem- -ber on said plate member, a throttle valve controlling -flow through said passageway and having a shaft journaled in said casing, an operating arm ilxed on said shaft, a fuel pump discharging into said passageway, a thrust member operatively connecting said throttle valve and said pump, and a cam follower member carried by said thrust member and cooperable with said cam member whereby movement of said supplemental supply valvev will actuate. said throttle valve.

` 5. A carburetor comprising a hollow casing having apassageway therethrough, main air and fuel inlets discharging into said passageway, a fuel reservoir supplying said 'fuel inlet, 'a throttle valve controlling'the discharge 'from said passageway and having a shaft journaled in said casing, an operating arm fixed on said shaft, a valve housing carried by said casing, a conduit leading from said reservoir to said housing, a

f conduit leading from said housing to said pasa conduit leading from said housing to said passageway on the outlet side of said throttle valve, a valve member in said housing having an operating member external of said housing, said valve member controlling communication between said nrst-named conduit and said second-named conduit and between said first-named conduit and said third-named conduit, a cam member movable by said operating member,a thrust member guided for reciprocation and operatively connected to said throttle arm, and a cam follower member fixed on vsaid thrust member and c`o operable with said cam member whereby movement of said valvemember will actuate said throttle valve.

6. A carburetor comprising a hollow casing having a passageway therethrough, main air and fuel inlets discharging into said passageway, a fuel reservoir supplying said fuel inlet, a throttle valve controlling the discharge from said passageway and having a shaft journaled in said casing,

an operating arm fixed on said shaft, a valve housing carried by said casing, a conduit leading from said reservoir to said housing, a conduit leading from said housing to said passageway on the inlet side of said throttle valve, a conduit leading from said housing to said passageway on the outlet side of said throttle valve, a valve memberin said housing having an operating member external of said housing, said valve member controlling communication between said first-named conduit and said second-named conduit and between said first-named conduit and said third-named conduit, a cam member movable by said operating member, a thrust member guided for reciprocation and operatively con-y nected to said throttle arm, a cam follower member fixed on said thrust member and cooperable with said cam member whereby movement of said valve member will actuate said throttle valve, suction operated valve means controlling said air inlet, and means actuated by said valve member for resisting operation of said valve means by suction.

7. A carburetor comprising a hollow body member having a passageway therethrough, main air and fuel inlets to said passageway, a fuel reservoir, a conduit leading from said reservoir to said fuel inlet, a valve'casing having a substantially cylindrical bore, a supplemental fuel supply oonduit leading from said bore and discharging into said passageway, a rotatable valve member in said bore and having a port registerable with said supplemental conduit, means to supply fuel from said reservoir to said valve casing and port, a cover member for said reservoir, said cover member having means supporting said valve member in operative position in said valve casing, and operating means to rotate said valve member.v

8. A carburetor comprising a hollow body member having a passageway therethrough, main air and fuel inlets to said passageway, a fuel reservoir, a conduit leading from said reservoir to saidfuel inlet, a valve casing having a substan, tially cylindrical bore, a supplemental fuel supply conduit leading from said ore-and discharging into said passageway. a rotatable valve member in said bore andhaving a port registerable with said supplemental conduit, means to supply fuel from said reservoir to said valve casingand port,

a cover member for said reservoir, said cover.

member having 'f means supporting saidvalve member in operative position in said valve casing, operating means to rotate said valve member,

and means cooperable with said operating means to hold said port in registrywith said supplemental conduit.

9. A carburetor comprising a hollow body member having a passageway therethrough, main air and fuel inlets to said passageway, a fuel reservoir supported by said member, a conduit leading from said reservoir to said fuel inlet, a pump housing positioned externally of and mounted on said reservoir and having a pump chamber, a piston reciprocable in said chamber, a fuel discharge conduit leading from said chamber to said passageway, an air inlet to said discharge conduit from said reservoir above the normal liquid level therein, a pump rod engaging said piston, means operable by said rod to close said second-named air inlet, a throttle valve controlling flow through said passageway, and means operatively connecting said throttle valve and said pump rod.

l0. A carburetor comprising a hollow body member having a passageway therethrough, main air and fuel inlets to said passageway, a fuel reservoir supported by said member, a conduit leading from said reservoir tol said fuel inlet, a pump housing positioned externally of and mounted on said reservoirand having a pump chamber, a piston reciprocable in said chamber, a fuel discharge conduit leading from said chamber to said passageway, an air inlet to said discharge conduit from said reservoir above the normal liquid level therein, a pump rod engaging said piston, means operable by said rod to close said secondnamed air inlet, a throttle valve having a shaft and controlling flow through said passageway, an operating arm fixed on said-shaft, and a thrust member having its opposite ends pivotally connected to said arm and to said pump rod.

il. A carburetor comprising a hollow body member having a passageway therethrough, main air andfuel inlets rto said passageway, a fuel reservoir positioned at one side of and supported by said body member, a conduit leading from said reservoir to said fuel inlet, a housing member positioned at one side of and supported by said reservoir, said housing member having a vertical cylindrical bore with its upper portion defining a valve chamber and its lower portion defining a pump chamber, a fuel supply conduit leading from said reservoir to said pump chamber, a hollow valve member rotatable in said valve chamber and having a vertical bore therethrough, a piston in said pump chamber, a pump rod extending through and slidably fitting in the bore of said valve member and cooperating with said piston, a combined air and fuel overflow chamber at the side of said valve chamber, said overiiow chamber having an air inlet port from said reservoir and having an air outlet port communicating with said valve chamber, said overflow chamber having a discharge port at its lower end communicatng with said valve chamber, said valve member having ports registerable respectively with said air outlet and discharge ports respectively, a discharge conduit leading from said pump chamber to the bore of said valve member, a supplemental fuel supply nozzle discharging into said passageway and communicating with said valve chamber, said valve member having a por?l to supply fuel to said nozzle, supplemental fuel supply means discharging into said passageway and communicating with said valve chamber, said valvemember having a port for supplying fuel to said supplemental means when said valve member is actuated to cut ofi fuel to said nozzle. said pump rod having means to close said overflow chamber discharge port and said nozzle,

a throttle valve controlling discharge from said passageway, means operable upon operation of said valve member to move said'throttle valve toward open position, suction operated valve means controlling said air inlet, and means operable upon operation of said valve member to resist opening movement of said valve means.

12. A carburetor comprising a hollow body` member having a passageway therethrough, main airand fuel inlets to said passageway, la fuel reservoir, a conduit connecting said reservoir and said fuel inlet, a pump chamber having fuel supply means, a discharge conduit4 extending upward from said chamber and discharging into said passageway, a piston in said chamber, and venting means opening into said chamber through a side wall thereof beneath said piston whereby liquid fuel will not be forced upward through said conduit by gas bubbles formed within or entering said chamber.-

13. A carburetor comprising a hollow body member having a passageway therethrough, main air and fuel inlets to said passageway, a fuel reservoir, a conduit connecting said reservoir and said fuel inlet, a pump chamber having fuel supply means, a discharge conduit from said chamber to said passageway, and a piston in said chamber, said reservoir having a port communicating with the upper end of said chamber beneath said piston whereby to relieve said chamber of vaporized gas.

14. A downdraft carburetor comprising a hollow body member having a passageway there-v through, a fuel supply conduit discharging into said passageway, a dash-pot chamber in said conduit having a piston provided with a valve port, s aid piston havinga hollow stem communiating with said port and defining a fuel nozzle, a metering valve cooperable with said port, valve means controlling air flow through said passageway and operatively connected to said stem, and a bleed port through said stem adjacent said piston establishing communication between the top of said chamber and the bore of said stem whereby fuel vapor or gas bubbles formed in said chamber can by-pass said valve port.

15. A carburetor comprising a hollow body member having a passageway therethrough, main air and fuel inlets to said passageway, a fuel reservoir supported by said body member, a conduit leading from said reservoir to said fuel inlet, a housingl member supported by said reservoir, said housing member having a vertical cylindrical bore with its upper portion dening a valve chamber and its lower portion defining a pump chamber, means to supply fuel from said reservoir to said pump chamber, a hollow valve member rotatable in said valve chamber and having a vertical bore therethrough, a piston in said pump chamber, a pump rod extending through the bore of said valve member and cooperating with said piston, a combined air and fuel overflow chamber at the side of said valve chamber, said overow chamber having an air inlet port and having an air outlet port communicating with said valve chamber,y said overow chamber having a discharge port at its lower end communicating with said valve chamber, said valve member having ports registerable respectively with said air outlet and discharge ports respectively, a discharge conduit leading from said pump chamber to the bore of said valve member, a supplemental fuel supply nozzle discharging into said passageway and communicating with said valve chamber, said valve member having a port to supply fuel to said nozzle, supplemental fuel supply means discharging into said passageway and communieating with said valve chamber, said valve member having a port for supplying fuel to said supplemental means, said pump rod having means to close said overow chamber air outlet port, said pump rod having means operable when said air outlet port is closed to establish communication between said overow chamber discharge port and said nozzle, and a throttle valv'e controlling discharge`from said passageway.

16. A carburetor comprising a hollow body member having a passageway therethrough, main air and fuel inlets to said passageway, a fuel reservoir supported by said body member, a conduit, leading from said reservoir to said fuel inlet, a housing member supported by said reservoir, said housing member having a vertical cylindrical bore with its upper portion defining member rotatable in said valve chamber and having a vertical bore therethrough, a piston in said pump chamber, a pump rod extending through the bore of said valve member and cooperating with said piston, a combined air and fuel overflow chamber at the side of said valve chamber, said overflow chamber having an air inlet port and having an air outlet port communicating with said valve char ber, said overflow chamber having a discharge port at its lower end communicating with said Valve chamber, said valve member having ports registerable respectively with said air outletand discharge ports respectively, a discharge conduit leading from said pump chamber to the bore of said valve member, supplemental fuel supply means discharging into said passageway and communicating with said valve chamber, said valve member having a port for supplying fuel to said supplemental means, said pump rod having means to close said -overllow chamber air outlet port, said pump rod having means operable when said air outlet port is closed to establish communication between said overflow chamber discharge port and said supplemental means, and a throtalsV tle valve controlling discharge from said passageway. v l i 17. A carburetor comprising a. throttle body member, a mixing chamber member and an air inlet member, said members being separable from each other and being rigidly secured together to provide an open-ended passageway, means controlling admission of air from said air inlet member to sai-d throttle body member, a fuel nozzle discharging centrally into said mixing chamber member and on the outlet side of saidv boss into said reservoir and discharging intothe other end of said open-ended conduit.

WILLIAM c. RAYFIELD. 

